﻿namespace SystemScanningGui.LoginUI
{
	using System;
	using System.ComponentModel.DataAnnotations;
	using System.ServiceModel.DomainServices.Client.ApplicationServices;
	using System.Windows;
	using System.Windows.Controls;
	using System.Windows.Input;

	/// <summary>
	/// Form that presents the login fields and handles the login process.
	/// </summary>
	public partial class LoginForm : StackPanel
	{
		private LoginRegistrationWindow parentWindow;
		private LoginInfo loginInfo = new LoginInfo();

		/// <summary>
		/// Creates a new <see cref="LoginForm"/> instance.
		/// </summary>
		public LoginForm()
		{
			InitializeComponent();

			// Set the DataContext of this control to the
			// LoginInfo instance to allow for easy binding
			this.DataContext = this.loginInfo;
		}

		/// <summary>
		/// Sets the parent window for the current <see cref="LoginForm"/>.
		/// </summary>
		/// <param name="window">The window to use as the parent.</param>
		public void SetParentWindow(LoginRegistrationWindow window)
		{
			this.parentWindow = window;
		}

		/// <summary>
		/// Handles <see cref="DataForm.AutoGeneratingField"/> to provide the PasswordAccessor.
		/// </summary>
		private void LoginForm_AutoGeneratingField(object sender, DataFormAutoGeneratingFieldEventArgs e)
		{
			if (e.PropertyName == "Password")
			{
				PasswordBox passwordBox = (PasswordBox)e.Field.Content;
				this.loginInfo.PasswordAccessor = () => passwordBox.Password;
			}
		}

		/// <summary>
		/// Submits the <see cref="LoginOperation"/> to the server
		/// </summary>
		private void LoginButton_Click(object sender, EventArgs e)
		{
			// We need to force validation since we are not using the standard OK
			// button from the DataForm.  Without ensuring the form is valid, we
			// would get an exception invoking the operation if the entity is invalid.
			if (this.loginForm.ValidateItem())
			{
				this.loginInfo.CurrentLoginOperation = WebContext.Current.Authentication.Login(this.loginInfo.ToLoginParameters(), this.LoginOperation_Completed, null);
				this.parentWindow.AddPendingOperation(this.loginInfo.CurrentLoginOperation);
			}
		}

		/// <summary>
		/// Completion handler for a <see cref="LoginOperation"/>. If operation succeeds,
		/// it closes the window. If it has an error, we show an <see cref="ErrorWindow"/>
		/// and mark the error as handled. If it was not canceled, but login failed, it must
		/// have been because credentials were incorrect so we add a validation error to
		/// to notify the user.
		/// </summary>
		private void LoginOperation_Completed(LoginOperation loginOperation)
		{
			if (loginOperation.LoginSuccess)
			{
				this.parentWindow.Close();
			}
			else if (loginOperation.HasError)
			{
				ErrorWindow.CreateNew(loginOperation.Error);
				loginOperation.MarkErrorAsHandled();
			}
			else if (!loginOperation.IsCanceled)
			{
				this.loginInfo.ValidationErrors.Add(new ValidationResult(ErrorResources.ErrorBadUserNameOrPassword, new string[] { "UserName", "Password" }));
			}
		}

		/// <summary>
		/// Switches to the registration form.
		/// </summary>
		private void RegisterNow_Click(object sender, RoutedEventArgs e)
		{
			this.parentWindow.NavigateToRegistration();
		}

		/// <summary>
		/// If a login operation is in progress and is cancellable, cancel it.
		/// Otherwise, close the window.
		/// </summary>
		private void CancelButton_Click(object sender, EventArgs e)
		{
			if (this.loginInfo.CurrentLoginOperation != null && this.loginInfo.CurrentLoginOperation.CanCancel)
			{
				this.loginInfo.CurrentLoginOperation.Cancel();
			}
			else
			{
				this.parentWindow.Close();
			}
		}

		/// <summary>
		/// Maps Esc to the cancel button and Enter to the OK button.
		/// </summary>
		private void LoginForm_KeyDown(object sender, KeyEventArgs e)
		{
			if (e.Key == Key.Escape)
			{
				this.CancelButton_Click(sender, e);
			}
			else if (e.Key == Key.Enter && this.loginButton.IsEnabled)
			{
				this.LoginButton_Click(sender, e);
			}
		}
	}
}
